Wouldn't this allow FTL communication? If you can input energy into an object and cause its state to be changed, you can input data. 1s and 0s. Positive or negative. Vibrating or not vibrating. Whatever. If, as this experiment was able to accomplish, you can entangle two objects so that they react as a single object because they have become quantumly linked, you could then conceivably separate the two objects over a large distance and use them to transmit data from the location of one to the location of the other instantly.

Theckhd wrote:big numbers are the in-game way of expressing that Brekkie's penis is huge.

No, because that's not how entanglement works. You can measure the two diamonds at different locations far apart, and those measurements will be correlated. But you can't control its state. It's not as simple as "do X to entangled particle #1, and entangled particle #2 experiences the same thing."

To put it another way, let's say the two particles are paired such that one is red (R), the other is blue (B). You don't know which one you've got until you measure it, nor does the person who has the other particle, light years away. You can both measure them at the same time, and you might find that you have the red one and he has the blue one. But no information has been sent between the two observers. I can't do something to one particle to influence the measurement in a way that has a deterministic effect on the second.

Klaudandus wrote:I thought measurement of an entangled state meant that given two entangled particles, if you know the spin of one, you already know the value of the other, regardless of distance.

In rough terms, yes. It's a little more nuanced than that, of course. For example, let's say you measure the spin of your particle. You instantly know the spin of the other one. Great. How do you send information with that? The guy at the other end knows what he measured, and can infer what you measured. But you had no way to control whether you measured a spin up or spin down, and neither did he. So no information gets transmitted in that scenario.

Anyway, the point is that there's no way to transmit information superluminally via entangled particles. Some papers call it "quantum teleportation," but it's just a fancy/flashy name. It's useful for secure quantum communications, but not for superluminal communications.

To make sure I understand you correctly: the problem with using this to transmit information is the fact that you could not do anything to one diamond that would definitively result in a known, determined effect, and that therefore you would not be able to predict what would happen?

I still can envision ways to transmit information that way though. For example (gross oversimplification, obviously), let's say you can do something to Diamond A which will cause it to spin, even if you don't know whether it will end up spinning up or spinning down.You still could transmit information by using the number of times the direction of spin changes to represent one piece of data, separated by a pre-determined pause of time.

Scientist Bob is on Earth with Diamond A.Scientist Steve is on a planet orbiting 51 Pegasi, 51 light years away, with Diamond B.The two scientists have some form of an agreed code where 1=A, 2=B, 3=C, etc.They also agree that they will allow 1 day to elapse between each letter. A slow way to transmit, yes, but orders of magnitude faster than a radio signal that has to travel 51 light years.

All Steve does is continuously measure Diamond B's spin, looking to see when it's spin changes in direction, and counting the number of times it does so.Bob wants to send a message beginning with the letter C, which is represented by 3 changes in spin direction.Bob shoots Diamond A with his laser. Measures Diamond A. It is spinning Up. Ok, we have a baseline.Bob shoots Diamond A with his laser. Measures Diamond A. It is now spinning down. Change in state #1. Steve, measuring Diamond B, observes this. Makes one tally mark on his message paper.Bob shoots Diamond A with his laser. Measures Diamond A. It is still spinning down. No apparent change as observed by Steve. No problem.Bob shoots Diamond A with his laser. It is now spinning Up again. Change in state #2. Steve makes a second tally mark off at 51 Pegasi.Bob shoots Diamond A with his laser. It is now spinning Down. Change in state #3. Steve makes a third tally mark.Bob sits and waits, making no more interactions with Diamond A for an entire 24-hour period. Steve observes no more changes in state over this long period of time. Enough period of time to make the uncertainty that Bob just happened to roll the 50-50 dice perfectly enough to have zero changes in state after hundreds of laser shots possible in that time period to negligible.Bob consults his codebook, and determines 3 state changes=C. Marks down C. Bob awaits the next letter the following day.

You see what I mean? You don't need known outcomes for data to still be possible to transmit. If you are capable of effecting any measurable change in the object at all as a result of your interaction with it, you can transmit data. What am I misunderstanding?

Theckhd wrote:big numbers are the in-game way of expressing that Brekkie's penis is huge.

To make sure I understand you correctly: the problem with using this to transmit information is the fact that you could not do anything to one diamond that would definitively result in a known, determined effect, and that therefore you would not be able to predict what would happen?

Exactly.

Brekkie wrote:I still can envision ways to transmit information that way though. For example (gross oversimplification, obviously), let's say you can do something to Diamond A which will cause it to spin, even if you don't know whether it will end up spinning up or spinning down.You still could transmit information by using the number of times the direction of spin changes to represent one piece of data, separated by a pre-determined pause of time.

Nope, because that doesn't work. Again, you can't deterministically do anything to one diamond and have it effect the other, because that's not what entanglement means.

Do something to change the spin of one diamond? You've just destroyed the entanglement, The same thing doesn't magically happen to the other diamond.

All entanglement means is that the two particles are correlated in a very special way. In other words, they're both Red or both Blue, or you'll always find them in pairs of RB or BR, something like that. Again, it's more nuanced, because entanglement is correlation in any "basis set," which is what makes it different from painting two ping-pong balls, putting them in boxes, and shipping them off to distant locations.

Basically, as long as you don't do anything to collapse the state, the two will remain entangled. Making a measurement collapses the state.

Brekkie wrote:Scientist Bob is on Earth with Diamond A.Scientist Steve is on a planet orbiting 51 Pegasi, 51 light years away, with Diamond B.The two scientists have some form of an agreed code where 1=A, 2=B, 3=C, etc.They also agree that they will allow 1 day to elapse between each letter. A slow way to transmit, yes, but orders of magnitude faster than a radio signal that has to travel 51 light years.

All Steve does is continuously measure Diamond B's spin, looking to see when it's spin changes in direction, and counting the number of times it does so.

Again, this is where the entanglement ends. They may make the first measurement, and find out that both particle were spin up. But at that point, they stop being entangled, and anything that Bob does to diamond A is completely independent of diamond B.

I see. The article made it sound like they were some kind of magical D&D item that was a pair that were forever linked and whatever one experiences, the other experiences. Kind of a romantic notion actually. Maybe my mind was on V Day.

Thanks for the break down.

Theckhd wrote:big numbers are the in-game way of expressing that Brekkie's penis is huge.

From what I gather, that's theoretically possible by getting close enough to the Event Horizon of a Black Hole without crossing it. It's technically more effective to actually get closer to the black hole, but once you cross the event horizon, the matter is getting out of the black hole.

Remember, just going faster already reduces your time compared to an static observer